The present invention relates to an improved energy management system and more particularly to an energy absorbing bumper system for a vehicle which both absorbs the energy of impact and permits a high strength bumper to deflect without being deformed to guide the vehicle on which it is mounted around a pole or similar obstruction with which the vehicle collides.
The present invention is a modification of the invention disclosed in my copending application Ser. No. 581,544, filed May 28, 1975, now U.S. Pat. No. 4,031,978, issued June 28, 1977.
In my prior U.S. Pat. No. 4,031,978, an energy management system is disclosed wherein the vehicle engine, transmission, and drive train are coupled to the vehicle bumper through an energy absorber unit so that the force of impact is opposed by this portion of the vehicle. In this system two additional energy absorber units are mounted on opposite sides of the central energy absorber unit and between the bumper and the frame of the vehicle. By the use of the foregoing system, the weight of the vehicle and bumper combination can be reduced by 25% without endangering the vehicle occupants in a collision because the momentum of the engine and its associated drive train is utilized to oppose the force of impact.
In the past, bumpers were made relatively heavy, that is, they generally weighed in the area of 60 to 70 pounds. Furthermore, they were made of relatively low yield strength materials, in the neighborhood of about 50,000 pound per square inch. Whenever a vehicle carrying a bumper of the foregoing type struck a pole, the momentum of the bumper tended to cause it to wrap itself around the pole because the portion contacting the pole yielded on impact while the adjacent portions tended to continue to move forwardly. This action essentially caused the vehicle to be captured by the pole and caused the kinetic energy of the vehicle to be reduced in an extremely short period of time, thereby causing the vehicle occupants to be thrown forwardly and ultimately causing the vehicle engine to be pushed rearwardly into the passenger compartment.